Sliding glass windows and sliding glass doors have come into widespread use in home construction. Such doors and windows are distinguished from conventional construction in that they slide in horizontal tracks rather than being lifted vertically in vertical tracks or swinging on a vertical hinge axis. Sliding glass windows and doors are generally considered to be more adaptable to different installations than conventional fixtures, to provide a more attractive installation, and to be easier to use and maintain. However, the installational and operational flexibility of such windows and doors also results in an installation that is difficult to securely lock. The locking or latching devices provided as part of such sliding panels typically do not prevent an intruder from lifting the sliding panel into the upper track sufficiently to clear the lower track so that the panel may be lifted completely free of the tracks, or at least sufficiently to permit the intruder to move the panel so that a wire or hook may be inserted between the sliding and fixed panels and utilized to operate the latch.
An increase in the crimes against property including vandalism and burgulary has made it increasingly important to secure sliding panels against unauthorized operation. As a result of widespread acknowledgement of the need, numerous sliding glass door and sliding window supplemental locks have been provided. One such device is in the form of a dead bolt which is permanently mounted on the track and is operated in and out of holes drilled through the window track. Such devices are sufficiently difficult to operate and they frequently fall into disuse. The required installation discourages widespread use and permanently disfigures the window or door track. Other devices have been provided which are intended to be temporarily applied to the window or track to secure the window against horizontal movement. However, such devices have typically not provide a sufficiently strong purchase againt the track or window to prevent the sliding panel from being forced open.
Therefore, it is desirable to have a sliding glass window and door lock that does not require permanent installation and yet securely locks the sliding panel against vertical lifting and horizontal sliding.